The Church of St. John the Baptist is a domed cruciform church, built of undressed stone. It is one of the best preserved churches in Nesebar. It is 12 meters long and 10 meters wide. The structure of the church consists of two cylindrical vaults which intersect in the center of the composition. The masonry is crushed stone and pebbles and the facades were probably smoothly plastered. It was built in the 11th century. The altar space consists of three semi-circular apses. Four massive pillars support the dome and form the cross. Inside the church the walls are smooth and unbroken. The exterior is simple without decorative niches and ceramic plaques, typical of the ornamental style. Bricks were used as a decorative element over the entrance, in the jagged cornices and around the windows.
Some frescoes in the church have been preserved dating from later periods. The faded portraits of the donor and his contemporaries on the southern wall and the fragments beneath the dome date from the 14th century and the others are from the 16th and 17th centuries.
Visby Cathedral (also known as St. Mary’s Church) is the only survived medieval church in Visby. It was originally built for German merchants and inaugurated in 1225. Around the year 1350 the church was enlarged and converted into a basilica. The two-storey magazine was also added then above the nave as a warehouse for merchants.
Following the Reformation, the church was transformed into a parish church for the town of Visby. All other churches were abandoned. Shortly after the Reformation, in 1572, Gotland was made into its own Diocese, and the church designated its cathedral.
There is not much left of the original interior. The font is made of local red marble in the 13th century. The pulpit was made in Lübeck in 1684. There are 400 graves under the church floor.